Machine for flash butt welding of pipes

ABSTRACT

Disclosed is a machine for flash butt welding of pipes located in the bore of the pipes welded together, a housing (2) whereof is provided with rigidly attached thereto a first supporting disc (3) and a second supporting disc (4) and with a pipe flashing-and-upsetting means (5) which has a carrier (7) and a hydraulic actuator (6) for displacing said means along the housing (2) and also has two pipe clamping means (9, 10) each whereof is provided with a carrier (12 and 13) and self-contained hydraulic actuators (11) imparting axial motion to this clamping means. 
     Bellcranks (24) located equidistantly apart all the way around the periphery of the outside surface of each carrier (12, 13) of pipe clamping means (9, 10) are pivitally attached thereto with provision for rocking in the radial direction, whereby one end of every bellcrank (24) interacts at one side (26) thereof with rigid stops (27, 31) provided on the first supporting disc (3) and on that side of the carrier (7) of pipe flashing-and-upsetting means (5) which faces the pipe clamping means (9, 10) the opposite side of the bellcrank end interacting with a spring-loaded stop (29) provided on the carrier (12,13) of each pipe clamping means (9,10), while the opposite end of every bellcrank (24) is provided with an aligning roller (25) contacting in inner wall of the pipes (1).

TECHNICAL FIELD

The invention relates to equipment for flash butt welding and hasspecific reference to machines for ring seam welding of pipes.

PRIOR ART

When a machine for flash butt welding is moved by a roller supporteddriving means from one butt joint to another through the bore of thepipe, the current-applying clamping blocks must stay clear of the innerwall of the axis of the displacing machine and that of the pipe or a toonarrow clearance between the current-applying blocks and the inner pipewall can cause the blocks to contact surface irregularities of the pipewall or remnants of flash thereon. Rapid wear of the current-applyingblocks and breakage or stoppage of the welding machine are thereforefrequent occurences.

Known in the art is a machine for flash butt welding of pipes (cf. USSRInventor's Certificate No. 286 103, Cl. 21h 29/10, 1969) in a housingwhereof there is secured a rod carrying pipe clamps each whereof isprovided with a flanged slider located on the rod with provision forlongitudinal displacement, whereby every slider interacts through aprojection with a turning lever carrying a supporting roller and throughthe flange with a bar of a spring-loaded block fitted to the housing.The tension of the springs acting on the blocks is selected depending onthe weight of the structure. If the radial displacement of a supportingroller exceeds that of the rest of rollers, as this may be the case whenthe inner wall of the pipe is elliptical, the turning lever of theroller concerned acts with its projection on the slider which transmitsthis action to the rest of rollers. This brings about a self-alignmentof the machine for flash butt welding throughout the process.

Nevertheless, to fit a new pipe to the machine for welding is a problembecause of the initial setting of the rollers which exceeds a maximumpossible pipe diameter, and much effort is required in order to overcomethe tensions of springs the rollers are subjected to.

Also known in a machine for flash butt welding of pipes, preferablythose of large diameter, (cf. USSR Inventor's Certificate No. 292 743,Cl. B23K 11/04, 1969) in a housing whereof there are provided clampingmeans, a flashing-and-upsetting means and two retaining means which arelocated at either end of the pipes welded together to sustain theupsetting force. The machine is provided with aligning rollers withindividual actuating means which cause the rollers to displace radiallytowards the inner walls of the pipes welded. The aligning rollers arefitted each to an end of a bellcrank and the other end of everybellcrank contacts a common disk which, being displaced along thehousing of the machine by an individual hydraulic actuator, causes therollers to swing about the fulcrum of every particular bellcrank so asto come closer to, or farther from, the inner walls of the pipes welded.An aligning mechanism of the above layout invites no difficulties infitting the welding machine into the hore of a new pipe.

However, this mechanism and the indiviudal means of actuating thealigning rollers complicate the construction and increase the weight ofthe machine. Additional operations which must be coped with duringwelding in this case render automatic control of the machine a problem.

Further known is a machine for flash butt welding of pipes whichoperates in the bore of the pipes welded together (cf. USA Pat. No.4,273,985, Cl. B23K 11/04, dated June 16, 1981).

The known machine for flash butt welding of pipes consists a housingwhich is aligned with the axis of the pipes welded and has a firstsupporting disc and a second supporting disc located its ends. A pipeflashing-and-upsetting means capable of displacing along the housing dueto individual hydraulic actuators is fitted to the housing with the aidof a carrier next to the second supporting disc. Means of clamping thepipes welded with carriers fitted to the housing and with individualhydraulic actuators serving to displace said means along the axis of thehousing are located the pipe flashing-and-upsetting means and the firstsupporting disc. The carriers of the pipe clamping means and the pipeflashing-and-upsetting means are fitted to the housing of the machinewith provision for axial displacement. A welding transformer isinterposed between the pipe clamping means.

To facilitate the machine travel in the bore of the pipes weldedtogether provision is made in the carriers of the pipe clamping devicefor supporting rollers pivotally mainted therein with aid of fulcrumpins.

Pipes are commonly manufactured to tolerances as large as, for example,±4 mm on the diameter and from +0.4 to -1.2 mm on the wall thickness.Apart from that, pipes can corrugate and may contain flash in their boreof a height between 8 and 20 mm. To negotiate these obstacles when thewelding machine is being advanced along the pipe bore to the next joint,the supporting rollers are fitted to the carriers of the pipe clampingmeans so as to stay clear of the inner wall of the pipe. In being movedalong the pipe bore, the welding machine is supported by the rollers andits axis therefore displaces out-of-true with the axis of the pipeline.Under such circumstances, the current-applying clamping blocks of themachine which are fitted with a limited free travel owing to the spacein the pipe bore being at premium graze the surface irregularities ofthe pipe wall and, as a result, rapidly wear away. Large lumps of flashmay even block the advance of the machine.

ESSENCE OF THE INVENTION

The object of the present invention is to provide a flash butt weldingmachine which is reliable in operation due to a new method of itsalignment during the travel down a pipe.

This object is realized by disclosing a machine for flash butt weldingof pipes which operates in the bore of the pipes welded together andcomprises a housing located in alignment with the axis of the pipes andprovided with a first supporting disc and a second supporting discs atthe ends; a pipe flashing-and-upsetting means with a hydraulic actuatordisplacing said means along the axis of the housing, a carrier of saidmeans being fitted to the housing next to the second supporting disc;two pipe clamping means with individual hydraulic actuators them alongthe axis of the housing, carriers of said two means being fitted to thehousing between the first supporting disc and the pipeflashing-and-upsetting means, wherein according to the inventionbellcranks pivotally attached to the outside surface of each carrier ofthe pipe clamping means are provided at least at three points spacedequidistantly apart all the way around the periphery of each carrierwith provision for rocking in the radial direction, and rigid stops areprovided on the first supporting disc and on that side of the carrier ofpipe flashing-and-upsetting means which faces the pipe clamping means,whereby every bellcrank is fitted with provision for interacting at oneside of its free end with one of said rigid stops which equal thebellcranks in number and at the outher side of said end with aspring-loaded stop provided on the carrier of every pipe clamping meansand the opposite end of every bellcrank is fitted with an aligningroller contacting the inner wall of the pipes welded together.

The rocking bellcranks which are provided with aligning rollers and arefitted to the carriers of pipe clamping means so as to contact the rigidstops at one side and the spring-loaded stops at the other side permitthe welding machine to be aligned with the axis of the pipe whilewelding every joint or being moved to the next joint. Idle strokes ofthe hydraulic actuators which operate the pipe clamping means facilitatethe alignment.

The disclosed machine for flash butt welding of pipes is of a lesscomplex design and of lighter weight than its predecessors. Its powerrequirements are also lower than ever before.

SUMMARY OF THE DRAWINGS

The invention will now be described by way of example with reference tothe accompanying drawings in which

FIG. 1 is a sectional elevation of the machine for flash butt welding ofpipes according to the invention;

FIG. 2 is a section on line II--II of FIG. 1;

FIG. 3 shows a bellcrank in contact with a rigid stop on the secondsupporting disc.

Referring to FIG. 1, the machine for flash butt welding of pipesaccording to the invention is located in the bore of the pipes 1 weldedand incorporates a housing 2 the axis whereof is aligned with the axisof the pipes 1. A first supporting disc 3 and a second supporting disc 4are fitted at the ends of the housing 2.

A pipe flashing-and-upsetting means 5 is located next to the secondsupporting disc 4. It can be displaced along the axis of the housing 2by an individual hydraulic actuator 6 and has a carrier 7 which islocated on the housing 2 of the machine with provision for displacementalong the axis thereof.

The hydraulic actuator 6 of the pipe flashing-and-upsetting means 5which causes this means to displace along the axis of the housing 2consists of hydraulic cylinders located symmetrically all the way aroundthe perimeter of the housing 2. The cylinders proper are rigidlyattached to the second supporting disc 4 and piston rods 8 are fastenedto the carrier 7 of the pipe flashing-and-upsetting means 5.

Pipe clamping means 9 and 10 with individual hydraulic actuators 11which displace them along the axis of the housing 2 are fitted to thehousing 2 by means of carriers 12 and 13, respectively, between the pipeflashing-and-upsetting means 5 and the first supporting disc 3. Thecarriers 12 and 13 of the pipe clamping means 9 and 10 are fitted to thehousing 2 with provision for displacing along the axis thereof. Awelding transformer 14 with flexible leads 15 is fitted to the housing 2between the clamping means 9 and 10.

The pipe clamping means 9 incorporate clamping arms 16 which are locatedequidistantly apart and symmetrically with respect to the axis of thehousing 2. Every clamping arm 16 pivots about a fulcrum pin 17 fittinginto the first supporting disk 3 with one end and is pivotally attachedwith its other end, which is next to the transformer 14, to a outwardthrusting toggle 18. This, in its turn, is pivotally attached to thecarrier 12 of the pipe clamping means 9 with its other end. Acurrent-applying clamping block 19 connected to a terminal of thetransformer 14 via a flexible lead 15 is fitted to that end of everyclamping arm 16 which is located next to the transformer 14.

The other pipe clamping means 10 is of the same layout as indicatedabove except that its every clamping arm 20 pivots about a folcrum pin21 fitting into the carrier 7 of the pipe flashing-and-upsetting means 5with one end and the current-applying clamping block 19 is connected tothe other terminal of the transformer 14 via a relevant flexible lead15.

The individual hydraulic actuators 11 of the pipe clamping means 9 and10 comprise each a plurality of cylinders located symmetrically all theway around the periphery of the housing 2. The cylinders proper of themeans 9 and 10 are rigidly attached to the carriers 12 and 13,respectively, and the piston rods 22 of the pipe clamping means 9 aresecured to the first supporting disc 3 where as the piston rods of thepipe clamping means 10 are held fast to the carrier 7 of the pipeflashing-and-upsetting means 5.

Bellcranks 24 capable of rocking in the radial direction about fulcrumpins 23 through slots provided in the outside surface of the carriers 12and 13 (FIG. 2) of the pipe clamping means 9 and 10, respectively, arelocated at least at three points spaced equidistantly apart all the wayalong the circumference of the carriers 12,13 (there are threebellcranks on every carrier 12 and 13 in the case under consideration).An aligning roller 25 contacting the inner wall of the pipes 1 weldedtogether is fitted to an end every bellcrank 24 with the aid of afulcrum pin.

The other end of every bellcrank 24 fitted to the carrier 12 of the pipeclamping means 9 is capable of contacting at one side 26 a rigid stop 27provided on that side of the supporting disc 3 which faces the pipeclamping means 9, the rigid stops 27 equalling the bellcranks 24 innumber, in this particular case, three (FIG. 2).

The opposite side 28 (FIG. 1) of the same end of the bellcrank 24 isadapted for contacting a spring-loaded stop 29 which is provided on thecarrier 12 of the clamping means 9 (the amount of the stops equallingthe bellcranks in number, that is, three in this particular case), thestop 29 being loaded with a spring 30.

The bellcranks 24 fitted to the carrier 13 of the pipe clamping means 10are of the same design except that each of them contacts at one side arigid stop 31 provided on the carrier 7 of the pipeflashing-and-upsetting means 5. The stops 31 equal the bellcranks 24 innumber (three in this case).

A pump unit 32 and a mechanism 33 with drive rollers 34 serve to advancethe machine for flash butt welding down the bore of the pipes weldedtogether.

In operation, a drive 33 (FIG. 1) advances the welding machine down thebore of a welded pipe section so that the front and of the machineextends outside the pipe 1, and the pipe end face is located exactlybetween the pipe clamping means 9 and 10, e.g. at a point where the nextweld will be applied.

The machine is disconnected from the power supply and a pipe 1 to bewelded is slipped on the front end of the machine until it comesabutting against the other pipe 1. The machine is connected to thesource of power and fluid is admitted into spaces A of the individualhydraulic actuator 11 of the pipe clamping means 9 under a pressure.

The piston rods 22 of the pipe clamping means 9 remain immovable, beingrigidly attached to the first supporting disc 3 which is secured to thehousing 2. Therefore set into motion are the cylinders and movingintegrally therewith along the housing 2 towards the joint is thecarrier 12 of the pipe clamping means 9. The clamping arms 16 which aremechanically linked to the carrier 12 move outwards and press thecurrent-applying clamping blocks 19 against the inner surface of thepipe 1. A further advance of the carrier 12 cause the clamping arms 16to clamp the pipe 1. Since the carrier 12 is coaxial with the housing 2and the clamping arms 16 are all of the same length and swing throughthe same angle, the pipe clamping means 9 sets the welding machine inalignment with the pipe 1. Their axes coincide with one another.

Thus, the machine has been clamped in the bore of the pipe for flashbutt welding and its axis has been brought into alignment with that ofthe pipe.

During the period elabpsed in clamping and aligning the machine in thepipe 1, the spring-loaded stops 29 (FIG. 1) come abutting against thefree ends 28 of the bellcranks 24 and, as a result, the opposite ends ofthe bellcranks 24 carrying the aligning rollers 25 move away from theinner surface of the pipe 1.

The pipe 1 to be welded is clamped by the clamping means 10 in the sameway as described above. The only difference is that the piston rods 22of the individual hydraulic actuator 11 of the pipe clamping means 10come abutting against the carrier 7 of the pipe flashing-and-upsettingmeans 5 which, in its turn, abuts against the second supporting disc 4attached to the housing 2.

At this stage, the pipe 1 to be welded is clamped and aligned with theaxis of the machine which has been already aligned with the axis of thepipe 1.

The welding transformer 14 is connected to a source of power and currentis applied to the clamping blocks 19 and hence to the pipes 1 over theflexible leads 15.

Simultaneously with applying the current, fluid under a pressure isadmitted into spaces B of the cylinders of the hydraulic actuator 6 ofthe pipe flashing-and-upsetting means 5. Since the cylinders areimmovable, being rigidly attached to the second supporting disc 4, thefluid admitted thereinto displaces the piston rods which are rigidlyfitted to the carrier 7 of the pipe flashing-and-upsetting means 5. Thecarrier 7 is set into motion as well and also moving is the pipeclamping means 10 which is linked to the carrier 7. The pipe 1 to bewelded gradually moves integrally with the clamping means 10, and theend faces of the two pipes 1 come close to one another so that flashingis brought about followed by an upsetting action. The pipes are weldedso together.

The fluid contained in spaces A and B of all hydraulic actuators sdrained therefrom and fed into the opposite spaces. All parts of themachine return into the original position. In displacing along thehousing 2 away from the weld, the carrier 12 of the pipe clamping means9 travels towards the first supporting disc 3 and the carrier 13 of thepipe clamping means 10 approaches the carrier 7 of the pipeflashing-and-upsetting means 5, whereby the current-applying clampingblocks 19 release their grip of the pipes 1 which have been weldedtogether. The carriers 12, 13 also cause the bellcranks 24 to contactwith their sides 26 the rigid stops 27 (FIG. 3) and 31 (FIG. 1) locatedon the supporting disc 3 and the carrier 7 of the pipeflashing-and-upsetting means 5, respectively.

During their further travel along the housing 2 of the machine, thecarriers 12, 13 of the pipe clamping means 9, 10 cause the bellcranks 24to press with their sides 26 against the rigid stops 27, 31. As aresult, the bellcranks 24 turn about their fulcrum pins on the carriers12,13 so that the aligning rollers 25 provided at the opposite ends ofthe bellcranks 24 come down on the inside surface of the pipes 1 weldedtogether (FIG. 3) and are pressed against same.

While the current-applying clamping blocks 19 (FIG. 1) release theirhold of the pipes with the assistance of the individual hydraulicactuators 11 of the pipe clamping means 9,10 as mentioned above, themachine stays in alignment with the axis of the pipes 1 welded togetherby virtue of the bellcranks 24 which are operated by the individualhydrualic actuators 11.

To apply a new pipe for welding without difficulty, the aligning rollers25 of the bellcranks 24 are displaced towards the centre of this pipe byadmitting fluid under a low pressure into spaces A of the hydraulicactuator 11 of the pipe clamping means 10. On fitting the pipe to themachine, fluid is admitted into the opposite spaces of the cylinderswhich press the aligning rollers 25 against the inside wall of the pipe1, keeping thus the axis of the machine in alignment with the axis ofthe pipe 1. To preserve the self-aligning ability of the machine inwelding pipes of a larger diameter or wall thickness, the tension of thesprings 30 must be adjusted.

The bellcranks 24 which are fitted with the aligning rollers 25 and areattached to the outside surface of the carriers 12, 13 of the pipeclamping means 9, 10, respectively, keep the welding machine in the boreof the pipe always in a coaxial position with the pipe 1 without anyspecial means of alignment. The alignment is brought about during theidling stroke of the cylinders of the individual actuators 11 of thepipe clamping means 9, 10 which return the carriers 12, 13 into theirinitial position preparatory to clamping a new pipe 1 for welding.

The disclosed arrangement of the carriers 12, 13 of the pipe clampingmeans 9, 10, respectively, which provides for fitting the bellcranks 24with their aligning rollers 25 to the outside surface of said carriersat least at three points spaced equidistantly apart along thecircumference of the carriers 12, 13 significantly widens the scope ofapplication of the machine for flash butt welding, simplifies itsconstruction, reduces weight and power requirements. An invariablyaccurate alignment of the machine in the bore of the pipe improves thequality of welds. This feature is of particular importance in layingtrunk pipelines when not excluded is the possibility that pipes withlarge tolerances on the diameter and wall thickness must be used.

INDUSTRIAL APPLICABILITY

The invention may be used to advantage in the field for welding togetherlarge-diameter sections of trunk pipelines carrying natural gas or oiland in stationary conditions as well.

What is claimed is:
 1. A machine for flash butt welding of pipes whichis located in the bore of the pipes (1) welded together and whichcomprises a housing (2) arranged coaxially with said pipes (1) weldingtogether and provided with a first supporting disc (3) and a secondsupporting disc (4) which are fitted to said housing at the oppositeends thereof; a pipe flashing-and-upsetting means (5) with a hydraulicactuator (6) serving to displace same along the axis of the housing 2, acarrier (7) of said means being located on the housing (2) of themachine next to the second supporting disc (4); two pipe clamping means(9, 10) with individual hydraulic actuators (11) for displacing samealong the axis of the housing, carriers (12, 13) of pipe clamping meansbeing located on the housing (2) between the first supporting disc (3)and the carrier (7) of the pipe flashing-and-upsetting meanscharacterized in that bellcranks (24) pivotally attached to the outsidesurface of each carrier (12, 13) of the pipe clamping means (9, 10) areprovided at least at three points spaced equidistantly apart all the wayaround the periphery of each carrier (12, 13) with provision for rockingin the radial direction about fulcrum pins (23) and rigid stops (27, 31)are provided on the first supporting disk (3) and on that side of thecarrier (7) of the pipe flashing-and-upsetting means (5) which faces thepipe clamping means (9, 10) whereby every bellcrank (24) is fitted withprovision for interacting at one side (26) of its free end with one ofthe rigid stops (27, 31) which equal the bellcranks (24) in number andat the other side (28) of the end, with a spring-loaded stop (29)provided on the carrier (12, 13) of every pipe clamping means (9, 10)and the opposite end of every bellcrank (24) is fitted with an aligningroller (25) contacting the inner wall of the pipes (1) welded together.